Production of sound ingots



Patented Jan. 12, 1932 PATENT OFFICE ANDREW G. OF YOUNGSTOWN, OHIOPRODUCTION OF SOUND INGOTS lio Drawing.

My invention relates to the production of sound steel ingots and hasparticularly in view certain operatin conditions that I have discoveredare beneficial and of great utility.

In my prior application, S. N. 318,190, filed at the rate ofapproximately 60 rising and falling jars per minute. Steel that issubjected to this treatment is remarkably free from slag inclusions. I

In carrying outmy aforesaid method of jarrin in actual" operation, Ihave discovered t at steel can be poured at much higher temperaturesthan heretofore, i. e., in a superheated conditiomand that high carbonsteels i. e. containing .from .15 C. to .60 C. can be poured withoutbeing killed.

It is desirable to pour steel at as high a temperature as possible,thereby eliminating the skulls in ladles and other wastage from tooquick chilling of the metal. The higher the temperature, however, thegreater the amount of occluded gases in the metal. If the steel is toohot when poured into the ingot mold, the metal becomes wild and isprojected out of the mold due to the rapid escape of occluded gases.

Since the metalloids or alloying materials are added in the ladle, aheat tapped at normal or below normal temperature will have a tendencyto leave some undissolved manganese, which in turn causes segregationand lamination, thereby causing serious loss in the finished product.Heats tapped at or below normal temperature have a tendency to hold thenon-metallic inclusions in suspension, but steel tapped at a highertemperature will cause a coagulation of thejnon-metallic inclusionswhich consequently rise to the surface and are thrown ofi. By jarringthe metal in, the mold during the pouring and in accordance with myinvention, the metal in the mold is kept in constant agitation, so

Application filed August 26, 1929. I Serial No. $88,637.

that any gases liberated can be expelled through the open top, and I amthus enabled to pour at the higher temperature with its attendantadvantages. Furthermore, as the metal is cooled, it loses its power forretaining the dissolved gases and much as is consequently given off, butthe body 0 the ingot is already solidified to the point where it isimpossible for the gas to escape through the top and as a resultblowholes are formed. so The amount of gases held in solution isdependent upon conditions under which the heat was made, the tapping temerature, teeming temperature and the carbon and manganese content of theheat. as

Steel to which a deoxidizer, such as silicon, has been added in theladle is known as killed steel, meaning that it is completelydeoxidized. Other steel is known as open steel.

High carbon steel i. e. containing above .15 (3., when poured withoutjarring must be killedfldue to the large amount of dis solved gases inthe metal. By jarring when pouring, I have discovered that I can makeopen steel up to .60 C. By making such steel open the yield can besubstantially increased and a better product for bending purposesproduced than with silicon or aluminum killed steel.

To the experienced open hearth operator, the mould action of steel is avery positive indicator of the quality of the heat. From experience ithas been found that ingots that drop or sink one or two inches in themoulds are usually thick skinned, which means deep seated blow-holes,consequently producing a better quality product; but ingots which riseor grow in the mould are thin skinned and have blow-holes very close tothe surface. This type of ingot produces a seamy and scabby product,unfit for a good quality product. Very often due to furnace conditionsand the manner in which a heat was worked down, a heat will drop in themoulds and then immediately begin to rise again. 'This also produces avery inferior product. Higher carbon open steels all have a tendency togrow in the moulds. This is particularly true of steels ranging from .15to .65 carbon. Heats tapped excessively hot also have a tendency to growin the moulds. By jarring the metal in accordance with my invention, itdoes not grow or rise in the moulds, regardless of the tappingtemperature or the carbon content.

Tapping steel at a higher than normal tapping temperature, i. e., in asuperheated condition has long been the aim of open hearth operators, asthere are a number of advantages to be gained, which are all ofiset if aheat is produced which rises in the moulds and causes the formation of athin skinned ingot. It is therefore evident that by jarring, the mouldaction of a heat tapped at a higher than normal temperature can becontrolled to produce ingots down in the moulds, which will insureingots reasonably free from segregation below the crop, uniformcomposition and comparatively free from non metallic inclusions, with acrystal structure widely different than non-jarred ingots, caused by thesetting of the crystals under the jar of the machine. .15 to .65 carbonsteel shows a very marked tendency to rise in the moulds, regardless ofwhether tapped on the high or low side of standard tapping temperature,but by jarring the same beneficial results will be realized as noted forsteel in the low carbon range.

The average open hearth practice is to tap heats at a temperature sothat a small skull remains in the ladle after the heat has been poured.The weight of the skull is used as an indicator of the tappingtemperature with a good tap. Since the temperature of the metal in themoulds is directly responsible for the type of mould action, it is theaim of steel makers to keep heats down in the moulds by tapping atstandard or below standard tapping temperature. The resulting product,naturally shows the defects which accompany cold heats. Heats tappedabove normal tapping temperature eliminates all skulls and by the use ofthe jarring machine, ingots tapped considerable above normal tappingtemperature, i. e., in a superheated condition can be made to drop inthe moulds, which produces thick skinned ingots; whereas, heats tappedabove normal tapping temperature and poured straight will rise in themould consequently producing thin skinned ingots.

Thick skinned ingots can be produced regardless of how high the tappingtemperature may be, although'the extreme temperature possible in an openhearth furnace is but 300-350 degrees higher than the normal tappingtemperature.

To determine whether the metal in the furnace is at normal tappingtemperature or above or below normal, the experienced open hearthfurnace operator may use different tests.

One of these is known as the spoon test. A long handled spoon or dipperof about the capacity of a drinking cup is inserted into the furnace anda spoonful of the slag which covers the bath is withdrawn. The spoon ismanipulated so as to secure an even coating of slag over the entireinner portion of the spoon. After this layer of slag has hardened, asecond layer of slag is applied in the same Way as the first layer. Thespoon-is then inserted deeply into the bath and a spoon full of moltensteel is withdrawn and is poured very slowly on the floor in front ofthe furnace. If a portion of the metal adheres to the slag coveredspoon, the metal is below normal tapping temperature. The amount belowthe normal tapping temperature is determined by the amount of steel leftin the spoon. If the metal clears the spoon, and does not cut the slagon the spoon, the heat is at a normal tapping temperature. If the metalclears the spoon but cuts out the slag on the spoon at the point wherethe metal is' flowing out, the heat is above the normal tappingtemperature. The amount above the normal tapping temperature is governedby the depth the slag is cut out.

Another test is known as the rod test. A steel rod 1%" square isinserted into the furnace-through a small opening in the door, and theoperator keeps the rod in motion by moving it to and fro very slowlyuntil the portion immersed in the liquid steel is burned ofl. Thebalance of the rod is then withdrawn and the condition of the burned endis noted. If the end is pointed or rat tailed the heat is below normaltapping temperature. If the end is burned off square the heat is atnormal tapping temperature. If the end is burned off square but thecorners of the rod, within a foot of the end, are chewed or bitten out,the heat is above the normal tapping temperature.

Assuming that the heat is in the ladle and the mould conditions arenormal, the steel pourer sets the jarring machine in operation beforethe stopper is opened, which allows the metal to flow into the moulds.The rate of jarring is of uniform speed throughout the operation. Thespeed however, is dependent upon the size ingot to be jarred. Thesmaller the ingot the more rapid the jar required. A deep narrow ingotrequires a quicker jar than a shallow wide ingot. In the latter .case,as low as twenty-four rising and falling jars may be suflicient.

From the above description it will be clear that my jarring processproduces surprising results in connection with certain operatingconditions for the production of steel ingots as will be hereinaftermore particularly set forth in the appended claims.

In my aforesaid copending application I have disclosed and claimed amethod of jarring steel upon which my herein described discoveries arean improvement. I do not carbon that are flat or the growing or risingof the gases through the open claim, broadly, herein that methodofjarring steel, although it may be used in connection with the claimedimprovements.

I claim 1. The method of producing high carbon steelingots containinflgfrom .15 carbon to .60 carbon that are at or down in the mold and have athick skin and deep seated blow-holes, comprising jarring in the moldthe high carbon steel which is made open.

2. The method of producing high carbon steel ingots containing from .15carbon to .60 carbon that are flat or down in the mold and have a thickskin and deep seated blow-holes, comprising jarring in the mold the highcarbon steel, which is made open and is jarred from the beginning ofpouring in order to keep it in such agitation as wil eliminate the largeamount of occluded gases through the open top of the mold beforesolidification of the metal, thereby inhibiting metal in the mold.

3. The method of producing steel ingots that are flat or down in themold and havea thick skin and deep seated blow-holes comprisingsuperheating the steel, pouring the steel in the mold in the superheatedcondition and jarring the steel in the mold from the beginning ofpouring in order to keep it in such constant agitation as will eliminatethe large amount of occluded gases through the open top of the moldbefore solidification of the metal, thereby inhibiting the growing orrising of the metal in the mold.

4. The method of producing high carbon steel ingots containing from .15carbon .to .60 down in the mold and have a thick skin and deep seatedblowholes, comprising superheating the steel, pouring the steel in themold in the superheated condition, and jarring in the mold the highcarbon steel, which is made open and is jarred from the beginning ofpouring inorder to keep it in such constant agitation as will eliminatethe large amount of occluded top of the mold before solidification ofthe metal, thereby inhibiting the growing or rising of the metal in themold.

In testimony whereof I aflix my signature.

ANDREW G. EGLER.

